Spring 1992
U.S. Department of Energy
Bioenergy Feedstock Development Program at
Oak Ridge National Laboratory

Energy Crops Forum was published periodically by the Bioenergy Feedstock Development Program, Environmental Sciences Division, Oak Ridge National Laboratory, managed by UT-Battelle, LLC., for the U.S. Department of Energy under Contract No. DE-AC05-00OR22725.

Table of Contents

• Switchgrass--Back to the Future
• Land Availability
• Priming the Energy Pump
• Switchgrass--A Model Species
• Publications of Interest

Switchgrass--Back to the Future

Pioneers who crossed the Great Plains in covered wagons tell of endless oceans of tall grasses. The root structure of these grasses formed the sod with which the early pioneers built their houses on the prairies and also provided the food for the bison. One of these native prairie grasses was switchgrass, a coarse-stemmed, hearty plant that grows to more than six feet in height, producing most of its growth in the warmest and driest months of the year. It is a perennial, coming up every spring from the previous year's root system.

Switchgrass (Panicum virgatum L.) is a leading candidate for use as an energy crop. It can produce 5-6 dry tons/acre or more of biomass annually. Switchgrass will take hold on newly cultivated soils within 1-3 years, depending on rainfall, soil fertility, and establishment techniques. The grass has soil-building qualities due to its deep root system that brings elements from deep soil horizons to the surface.

Switchgrass production for energy could simulate the natural ecosystems of the Great Plains. Today's remaining prairies have lost much of their diversity and vigor because of monocropping and lack of invigorating fires. The removal of the grass for energy production would mimic nature's methods of removal through fire and herbivore grazing.

With energy cropping, enough material would be left on the ground through the winter to protect the soil and wildlife. The byproducts from the conversion processes could be put back on the land along with some nitrogen, replenishing the nutrients taken off in the harvest.

Production and harvesting of grasses are common agricultural procedures. The agricultural infrastructure and the social acceptability needed for larger production of the crop are in place. The preferred harvest techniques are a one-cut system in which the cutting is done after the first killing frost and a two-cut system in which the first cutting is made midsummer and the second occurs after the first frost. The two-cut system appears to have the higher yield but the yield difference may not justify the additional cost.

The energy potential from switchgrass in Iowa is significant. The federal agricultural programs have idled more than 3.3 million acres of farm land in the state. These programs were set up to reduce the amount of feed grain crops being grown and to prevent soil erosion. As part of the agreement for idling the land, the farmer is given a yearly cash payment or allowed to participate in a price-guarantee program for the current crop. If the 3.3 million acres were used for switchgrass, producing 6 dry tons of material per year, and the material were then converted to ethanol, yielding 100 gallons of ethanol per ton of material, 1.98 billion gallons of ethanol would be produced annually. To place this in perspective, in 1990 Iowa used 1.3 billion gallons of gasoline.

Bringing this scenario about may not be as complex as one might initially think if federal money were used to build conversion plants instead of paying farmers not to produce grain crops. Many farmers and landowners have indicated a willingness to consider producing biomass for energy. Relatively small conversion facilities might be built in county seat towns. This would guarantee a market for the grass crop that the farmer could grow and provide the demand pull necessary to establish a new industry. It would also establish a new crop in rural America; continue grain crop acreage reduction, minimizing oversupply; provide for rural revitalization by adding new jobs; lower or eliminate farm-subsidy payments; limit nonrenewable energy dependence; provide for better air quality; and lessen the contribution to global warming.

The groundwork is done. Now may be the time for the unified push that is needed to propel this scenario from dream to reality. The process will not be easy, but it is necessary.

Edward L. Woolsey; Environmental Specialist; Iowa Department of Natural Resources

Land Availability

If biomass energy is to contribute significantly to the U.S. energy base, a large land base must be dedicated to growing energy crops. In a recent study, the National Resource Inventory (NRI) Database and information on expected energy crop yields were used to assess what land base in the United States might be capable of growing energy crops and how much biomass could be produced on that land.

The NRI database contains land use and agricultural capability information for more than 800,000 systematically selected locations on nonfederal lands and is designed for regional- and national-scale analyses of land use. To determine the land base that could support energy crops, the database was first queried to determine what land was cropland or had a good potential for conversion to cropland. Tables were developed to identify where that land occurred and its agricultural quality. In this manner, the gross land base for growing energy crops in the United States was characterized. To determine the amount of biomass feedstock that might be grown on that land base, biomass researchers were asked about the standing yields they would expect on land of varying agricultural capability in specific U.S. regions. From this information, a table of expected energy crop yields by location in the country and land agricultural capability was generated. Merging information from this table with information on land use and quality from the NRI resulted in regional statistics on land base and probable yield.

The land base identified includes 392 million acres capable of growing energy crops in the United States, and most of this land (359 million acres) is currently used for growing crops. If only land with a probable biomass feedstock yield of 5 dry tons/acre-year or greater is considered, the land base shrinks to 324 million acres in the case of herbaceous energy feedstock and 225 million acres in the case of short-rotation-woody-crop energy feedstock. If these acres were put into energy feedstock production, 2423 million tons of herbaceous biomass energy feedstock or 1427 million tons of woody feedstock could be produced annually. If only woody feedstock were produced, more than 57% would come from the North Central region, 20% from the South Central, and 10% from the Southeast and Northeast. About the same proportions occur if one considers only herbaceous feedstock production. The analysis points out that given current yield assumptions, herbaceous crops could capture a larger land base than woody crops, and more important, most of the land suitable for energy crops lies in the North Central region.

Biomass feedstock crop production, of course, competes with more conventional crop production. Only a portion of the identified land base could ever be dedicated to energy crops. On the basis of projections of future agricultural production and markets, perhaps 30 million-40 million acres could be dedicated to energy crops before these crops would begin to compete with and displace other agricultural products.

Priming the Energy Pump

The North Central region of the U.S. has more land suitable for growing energy crops than any other area of the country. Although it is not possible to calculate exactly how much land is available for energy crop production in the region, some land is available now and more is likely to be available in the future. Not only is land available, but the region also has more technical expertise and research data on growing energy crops than any other region. Equally important is the fact that many organizations are extremely interested in developing new land uses. This combination is ideal for the development of new biofuels industries.

A considerable portion of the U.S. Department of Energy's (DOE) Biofuels Feedstock Development Program's research budget is devoted to "priming the pump" in the area. Switchgrass and several other grass species are being evaluated for their biomass potential in screening trials in Iowa and North Dakota. New switchgrass germplasm, collect from eight mid-western states, is being tested at research sites in Indiana, Iowa, and Nebraska. Wood energy crop research includes a major breeding effort at Iowa State University to produce new hybrid poplar and eastern cottonwood clones adapted for the territory. Supporting the breeding effort is physiological modeling and biotechnology research being conducted by the U.S. Forest Service (USFS) in Rhinelander, Wisconsin, and at Michigan State University. Hybrid poplar clones in 10 and 20 acre blocks have been planted in Minnesota, North Dakota and South Dakota, and Wisconsin to investigate operational and environmental aspects of producing wood energy crops. This project is cost-shared by DOE, USFS and the Electric Power Research Institute.

Current wood energy crop research builds heavily on the pioneering work that has been conducted since the mid-70s by the North Central Forest Experiment Station in Rhinelander, Wisconsin. This work identified the potential of energy crops in the region and has yielded a solid base of information about hybrid poplars that is beginning to attract interest among private industries and farmers. The next Energy Crops Forum will feature highlights from the past 15 years of woody crops research in Wisconsin and exciting new developments in Minnesota.

Robin Graham

Switchgrass -- A Model Species

In order to meet the future need for cellulosic feedstock for conversion to ethanol, biofuels production strategies will have to rely on species capable of high production across diverse, often poor quality sites, with minimum adverse effects to the environment. As these needs are considered, it has become increasingly clear that herbaceous as well as woody crops will be required to maintain a stable supply of biofuels feedstock.

Having spent the past 6 years screening 44 herbaceous species, the Biofuels Feedstock Development Program (BFDP) is intensifying efforts to develop herbaceous crops as a significant component of a biofuels production strategy. The decision to focus initially on switchgrass as a model species is based on the premise that the most efficient use of current resources involves intensive research on one desirable species rather than more fragmented work on several.

As an endemic species of the tall grass prairie, switchgrass grows naturally across a wide range of sites extending from Canada to South America. This broad adaptation is evidenced by the fact that both lowland and upland ecotypes exist. The very active and deep rooting system equips the species to deal with marginal sites where water and nutrients limit less hardy species. The regional yields for switchgrass suggest it is an ideal energy crop due to its perennial growth habit, relatively low fertilization requirements (a factor in reducing production costs), and year-round ground cover for erosion control. Important to its reliability for both the supplier and biofuels production facilities are its rather high and stable biomass yields even in drought years.

The table below summarizes seven studies funded by BFDP. Maximum and minimum yields obtained during a representative, postestablishment year show the range in variation of performance over different soil and site types. Clearly site selection will be important to the attainment of high yields. The highest yields achieved to date have come from the lowland ecotypes, `Alamo' and `Kanlow', grown in the South Central region. Auburn University investigators David Bransby and Susan Sladden have achieved yields of approximately 15 dry tons/acre in 2 successive years in their research plots in Alabama.

With respect to environmental concerns regarding intensive biofuels production, switchgrass also appears to be a winner. Research at Virginia Polytechnic Institute by Lee Daniels and his students indicates that switchgrass can actually improve soil quality on marginal sites with its deep rooting pattern. Studies at Iowa have documented very low erosion rates and low nitrogen loss by leaching for switchgrass compared to conventional row crops. In addition, increased food and cover for wildlife are other important environmental considerations for this remarkable species.

As good as this crop is, it can be made even better through additional breeding and production-oriented research. Recently initiated BFDP-funded research will proceed across four fronts: classical breeding and selection techniques; physiological studies to identify short-term criteria for promoting and monitoring yield improvement; tissue culture to assist in production and protection of new cultivars; and permanent field plots designed for documentation and cultural improvement of longer-term yield potential. The first pilot-scale biofuels facilities for production of ethanol from cellulose are expected to be built in the late '90s. As these plans near completion, the availability of improved herbaceous varieties and production techniques will be very important to the critical challenges of interfacing bioproduction and bioconversion on a timely scale.

Jacqueline Martin and Sandy McLaughlin

Publications of Interest

1. Bransby, D. I., S. E. Sladden, and D. D. Kee. 1990. Selection and Improvement of Herbaceous Energy crops for the Southeastern USA. Final Report on a Field and Laboratory Research Program for the period March 15, 1985 to March 14, 1990. ORNL/Sub/85-27409/5. 76 pages.
2. Cherney, J. H. K. D. Johnson, J. J. Volenec, E. J. Kladivko, and D. K. Greene. 1990. Evaluation of Potential Herbaceous Biomass Crops on Marginal Crop Lands: 1) Agronomic Potential. Final Report 1985-1989. ORNL/Sub/85-27412/5&P1. 34 pages.
3. Dobbins, C. L., P. Preckel, A. Mdagri, J. Lowenberg-DeBoer, and D. Stucky. 1990. Evaluation of Potential Herbaceous Biomass Crops on Marginal Crop Lands: 2) Economic Potential. Final Report 1985-1989. ORNL/Sub/85-27412/5&P2. 84 pages.
4. Parrish, D. J., D. D. Wolf, W.L. Daniels, D. H. Vaughn, and J. S. Cundiff. 1990. Perennial Species for Optimum Production of Herbaceous Biomass in the Piedmont. Final Report 1985-89. ORNL/Sub/85-27413/5. 115 pages.
5. Pfeifer, R. A., G. W. Fick, D. J. Lathwell, and C. Maybee. 1990. Screening and Selection of Herbaceous Species for Biomass Production in the Midwest/Lake State. Final Report 1985-1989. ORNL/Sub/85-27401/5. 99 pages.
6. Thomas, D. L., M. A. Breve, P. L. Raymer, N. A. Minton, and D. R. Sumner. 1990. Improving Rapeseed Production Practices in the Southeastern United States. ORNL/Sub/86-91324/1. 42 pages.
7. Wright, N. 1990. Screening of Herbaceous Species for Energy Crop Production. Final Report 1985-1990. ORNL/Sub/85-27411/5. 85 pages.